Air root pruning of the root structure of a growing plant is well-known from, for example, the specifications of Australian Patent Nos 611917, 629067, 674543 and that of Petty Patent No 701466.
These specifications all generally disclose a plant growth container having a side wall formed from a cuspated sheet having holes formed in at least some of the outwardly projecting cusps to facilitate air root pruning of the root structure of a plant grown within the container. The side wall of the container is generally formed from a plurality of similar panels which are fastened together in various ways.
For example, Australian Patent No 611917 describes a method and container for growing transplantable plants, the container comprising a set of identical upwardly extending side panels which are removably joined together at their vertical edges by two sets of mortise and tenon joints positioned in spaced relationship on the panels. One set of mortise and tenon joints when connected is said to prevent lateral movement between the side panels, whilst the second set is said to prevent longitudinal movement therebetween.
Australian Patent No 629067 describes fastening means to hold a cuspated sheet in overlapping, nested engagement. The fastener disclosed comprises a rivet or releasable fastening means in the form of a strap or tie which passes through aligned holes at the overlap, or an adjustable strap or belt which extends around the circumference of the container.
Australian Patent No 674543 describes a resilient fastener in the form of a clip which engages either side of two overlapping edge portions of a panel which form the vertical sides of the plant growth container.
Australian Petty Patent No 701466 describes a cuspated sheet being arranged with a first edge portion overlapping either an opposite second edge portion of the same sheet or a second edge portion of another similar sheet, the protuberances of the outer surface of the second edge portion nesting within the recesses of the inner surface of the first edge portion to align openings in the protuberances at the overlap. At least one screw threaded fastener is located within the aligned openings, the fastener having a helical threaded shank and an enlarged head on one end of the shank, the threads having a sufficiently large depth between a crest of the thread and the shank to enable, in use, secure retention against the inner surface of the overlapping portions of the sheet or sheets thereby securing the overlapping edge portions together.
It has been observed that the fastening arrangements disclosed in the above specifications have a number of shortcomings. In the case of fasteners in the form of screws or rivets, it has been observed that the formation of a container using fastening means in that form can be time consuming, particularly in cases where a drill, rivet gun or screw driver is required to secure the panels together. Fastening of the container in that way can also lead to significant difficulties in readily dismantling the container.
In the case of a fastener in the form of a wire clip, the open-ended nature of the clip can lead to hand or finger damage to a user when attempting to secure the clip to the container. In addition, the strength of the fastening is to a great extent dependent on the degree of resilience of the material from which the clip is formed, which is likely to degrade over time, reducing the efficacy of the clip. Furthermore, the clip arrangement can require significant overlap of the edge portions of a sheet or adjacent sheets, at least partially (and in some cases significantly) reducing the number of cuspations available for air root pruning.
The foregoing does not constitute an admission as to the state of common general knowledge in the art as it existed at the priority date of a claim of this application.